Use of soy products and vegetarianism do not appear to protect against breast cancer

Vegetarian Journal, April-June, 2008 by Reed Mangels

Rates of breast cancer are lower in Asian women than the rates in the United States. Many reasons have been proposed to explain this difference, including greater use of soy products and lower meat consumption in Asian women following traditional diets. British researchers examined close to 38,000 women to investigate the possible link between soy use, vegetarian diet, and breast cancer risk. Close to one-third of the women said they did not eat meat or fish. More than half of the women ate soy products at least once a month; 37 percent used soy products at least weekly. Daily soymilk use was reported by 8 percent of the women. Vegetarian women had a higher intake of soy isoflavones than did non-vegetarian women. During the approximately 7-year-long study period, 1.6 percent of the women were diagnosed with breast cancer. There was no association between a vegetarian diet and risk of breast cancer. In other words, a vegetarian woman had the same risk of having breast cancer as did a non-vegetarian woman. There was also no association between isoflavone intake and breast cancer risk. This study was not able to address the possibility that use of soy products in childhood and adolescence could reduce the risk of breast cancer later in life.

Travis RC, Allen NE, Appleby PN, et al. 2008. A prospective study of vegetarianism and isoflavone intake in relation to breast cancer risk in British women. Int J Cancer 122:705-10.

By Reed Mangels, PhD, RD, FADA